Integer Overflow Vulnerability in libssh2: Remote Code Execution Risk
Summary
UBUNTU-CVE-2019-3855: An integer overflow flaw which could lead to an out of bounds write was discovered in libssh2 before 1.8.1 in the way packets are read from the server. Affects libssh2 versions < 1.4.3-2ubuntu0.2+esm1. Fixed in 1.4.3-2ubuntu0.2+esm1. How to fix ↓
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Background
libssh2 is a widely used library that provides an API for implementing SSH2 (Secure Shell) protocol in applications. It enables secure file transfers and remote command execution over unsecured networks. The library is essential for developers who need to integrate SSH capabilities into their software. However, a critical vulnerability has been identified in libssh2 that could allow attackers to exploit the library's functionality, leading to severe security risks.
Vulnerability Detail
An integer overflow flaw was discovered in libssh2 versions prior to 1.8.1, specifically in the way packets are read from the server. This vulnerability can lead to an out-of-bounds write, allowing a remote attacker who compromises an SSH server to execute arbitrary code on the client system when a user connects to the server. The potential ramifications include unauthorized access, data breaches, and system compromise, making it crucial for users to address this vulnerability promptly.
How To Fix
Minimum fixed version
1.4.3-2ubuntu0.2+esm1
This is the first release that contains the fix.
sudo apt-get install --only-upgrade libssh2Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, users can limit access to the SSH server or disable SSH connections until the package is updated. Additionally, consider using firewall rules to restrict access to the affected services.
Conclusion
The integer overflow vulnerability in libssh2 poses a significant risk to users, allowing remote code execution through compromised SSH servers. It is essential for users to update their libssh2 packages to the latest patched versions to mitigate this risk. Regular monitoring for vulnerabilities, such as through Vulert, can help maintain the security of applications.
See every vulnerability recorded for libssh2 →
FAQ
The CVSS score of this vulnerability is 7.5, indicating a high level of risk.
Versions of libssh2 prior to 1.8.1 are affected by this vulnerability.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
The vulnerability could allow remote attackers to execute arbitrary code on client systems, leading to unauthorized access and potential data breaches.
Yes, patched versions of libssh2 are available for Ubuntu users. It is recommended to update to the latest versions as specified in the 'how to fix' section.
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